Receiving errors when blending between multiple textures

Hello, I am following along with the documentation regarding multiple texture blending for vertex painting and I am receiving multiple errors in my Material Editor:

[SM5] /Engine/Generated/UniformBuffers/Material.ush(47,14-41): error X4510: maximum ps_5_0 sampler register index (16) exceeded
[SM5] /Engine/Private/LightmapData.ush(48,3-41): warning X3550: array reference cannot be used as an l-value; not natively addressable, forcing loop to unroll
[SM5] /Engine/Generated/Material.ush(2371,2-47): warning X3206: implicit truncation of vector type

Not sure what any of this means, but if anyone could shed some light, it is breaking my material. This only seems to happen with either my “Normal” textures or my “Roughness” textures. Albedo, Displacement, and AO all behave fine. I’ll attach some images to help show my set up.

Thank you

hey there !
it seems you are using more than the 16 sampler limit.
you should try to change a few samplers parameter :
go to a sampler source, a change it to shared.
it should work